Bromodeoxyuridine is a radiation sensitizing drug which sensitizes rapidly dividing cells. Thymadine is replaced by the uridinedeoxyriboside compound predisposing DNA 2 single strand breaks. BUdR has been used in the past in head and neck lesions, osteosarcoma, and particularly in glioblastoma and other brain tumors, but was felt to need intra-arterial delivery to be effective.